Epidermal Overexpression of Stratum Corneum Chymotryptic Enzyme in Mice: A Model for Chronic Itchy Dermatitis

Identification of tissue-specific mechanisms involved in the pathophysiology of inflammatory skin diseases could offer new possibilities to develop effective therapies with fewer systemic effects. The serine protease stratum corneum chymotryptic enzyme is preferentially expressed in cornifying epithelia. We have previously reported on increased expression of the stratum corneum chymotryptic enzyme in psoriasis. Here is reported an increased epidermal expression of stratum corneum chymotryptic enzyme also found in chronic lesions of atopic dermatitis. Transgenic mice expressing human stratum corneum chymotryptic enzyme in suprabasal epidermal keratinocytes were found to develop pathologic skin changes with increased epidermal thickness, hyperkeratosis, dermal inflammation, and severe pruritus. The results suggest that stratum corneum chymotryptic enzyme may be involved in the pathogenesis of inflammatory skin diseases, and that stratum corneum chymotryptic enzyme and related enzymes should be evaluated as potential targets for new therapies

Expression of stratum corneum chymotryptic enzyme in human sebaceous follicles

Stratum corneum chymotryptic enzyme (SCCE) may be involved in desquamation, a process necessary for maintaining a normal anatomy at all sites where there is continuous turnover of cornified epithelia. Using immunohistochemistry and in situ hybridization, we have, in this work, analysed SCCE expression in the sebaceous follicle. We found expression of SCCE in luminal parts of the pilary canal, common sebaceous ducts and proximal sebaceous ducts. In addition, SCCE was seen in cells apparently situated within the distal parts of the glandular lobules. Co-expression of SCCE and keratin 10 was seen only in the pilary canal and the common sebaceous ducts. The results give further support for SCCE being involved in desquamation-like processes. The association with cornification seems to be more general for SCCE than for keratin 10. The possible role of SCCE in diseases involving disturbances in the turnover of cornified cells in the sebaceous follicle, such as acne vulgaris, is a question for future studies